Five Pesticides On Soil Enzyme Activities

Soil enzyme is one of the factors in the course of soil metaboly. It plays an important role in the soil substance recycle including biochemical process. Pesticides may enter the soil by agriculture practices et al. The influence of pesticides on soil enzymatic activities was founded. Thus soil enzymes can be regarded as indicators to direct the impact of pesticides on soil environment. At present the area of plastic shed field is ever-increasing. The application quantity of pesticides is also increasing which results in the serious pesticide residues in soils and vegetables but the related studies are few.Influence of five pesticides (Chlorothalonil, Carbendazim and their mixture, Imidacloprid, Cypermethrin) on the activity of invertase, urease and hydrogen peroxidase in plastic shed, vegetable fields in Changchun suburb and campus field was determined. The relationship among soils' properties and influence of pesticides on the soil enzymatic activities were investigated.The results showed that invertase activity in soil was strongly inhibited by Chlorothalonil, Cypermethrin and the mixture of Carbendazim- Chlorothalonil in the range of trial concentration between 0.1mg/g and 50mg/g. Under the concentration of 0.1mg/g of Carbendazim and Imidacloprid the invertase activity was stimulated, and inhibited under the effect of high concentration(﹥0.5mg/g). The joint effects of Carbendazim and Chlorothalonil were much more than each single pesticide.The urease activities were stimulated in the effect of five pesticides, with stronger influence at higher concentration except Imidacloprid. Influence of Cypermethrin on the urease activities was the highest. Under the low concentrations (0.1,0.5,1mg/g) of Chlorothalonil, Carbendazim and the mixture of Carbendazim-Chlorothalonil the activation were not clear, while the activation rate still less than 20% under the concentration of 10mg/g and 50mg/g. The activation rate of Imidacloprid under the concentrations of 1mg/g and 10mg/g was about 20%, higher than the other concentrations.Under the low concentration of 1,10,40 μg/g, the process of influence on the hydrogen peroxidase in two soils was stimulation first, then recovery after the application of Carbendazim and Cypermethrin. The inhibition was fairly strong under the effect of high concentration (150μg/g). The inhibition in plastic shed soil was much stronger than in vegetable field soil.The inhibition of Carbendazim to the invertase activity was weakest in campus soil. The stimulation to urease activity was weakest in plastic shed soil.In summary, the relationship among pesticides concentration, soil enzymatic activities and soil physiochemical properties were studied in certain degree in this dissertation. Those could provide valuable scientific evidences for the furthermore studies on the environmental risk evaluation and reasonable application of pesticides in plastic shed field.